Welcome to WGT Cerebral Assassin.... (2Stupid2Live also - might find some value in this)
Enjoy yourself here. TO answer your questions and to offer some of my own experience....
I joined in February and I did just fine with the Starter Clubs and Starter Ball - I was able to advance first to Amateur and then to Pro without ever purchasing upgraded clubs.
I was able to ENJOY MYSELF and work at improving my game JUST FINE (for MONTHS!) with the Starter set.
I think sometimes for newer players it feels a bit overwhelming with all of the choices - don't overwhelm yourself - just work on your game, getting your shots placed well and certainly your putting. You will be able to do this with the Starters. Sometimes newer players feel like they have to advance through the levels all at once - but at the end of the day whether with upgraded gear or not, you STILL have to be able to hit the shots! So practice well with your starters...and enjoy yourself (even though some frustration comes with that it is all a part of it).
When I reached Pro Level, there came a point where I felt I had improved my game as far as I could and at that point I upgraded DRIVER ONLY - after some time in the Pro Tier and when trying to attain Master, for reasons of DISTANCE (because each higher tier pushes your tees BACK further) you will want to upgrade your Driver - but that is probably some weeks or months away depending on how much you play.
THE BOTTOM LINE ON CLUB UPGRADES: (My Philosophy - others may differ) Take your game as far as you can take it with the Starters AND THEN consider club upgrades. At the end of the day, if you buy upgraded clubs and still can't hit the shots, the clubs won't correct that for you - and might even lead to frustration because you "just spent a bunch of money" and still can't get the approaches near the hole or your putts IN the hole - there are instances of this abound on WGT. LOL
Some interesting History: WGT was a far different place back in February 2009 when I joined - and I daresay far less "overwhelming" when I was a new player compared with now. The only Stroke Play Course was Kiawah - and it was the FRONT 9 ONLY. There was also a CTTH on Kiawah and also a CTTH on Bali Hai BUT THAT WAS IT. There was no Master Tier at all - Pro was the Top - Master Tier appeared in late May. In fact - if Memory Serves me, I don't think there was even ANYTHING yet stocked in the Pro Shop! I feel like it had some static message that said "Coming Soon to WGT" or something like that. Times have changed.
Final note: IF considering upgrading ANYTHING - consider a ball upgrade - it is a "cheap" thing you can do without a major investment and it allows you to add a minor bit of enhancement to how your game is working without a major investment.
Enjoy Yourself Here! AtlantaCoaster